Extracción de hidrocarburos aromáticos de corrientes de refinería con líquidos iónicos como disolventes. Determinación de los coeficientes de difusión, interacciones químicas y toxicidad

"Introducción" Los líquidos iónicos llevan siendo estudiados desde hace más de dos décadas como una nueva generación de disolventes para diferentes aplicaciones en la industria química. Son sales compuestas por cationes orgánicos y aniones tanto orgánicos como inorgánicos que representan puntos de fusión inferiores a 373,2 K. Sus principales características, tales como su carácter no volátil, alta estabilidad térmica y elevada capacidad de diseño mediante la selección de los iones de su estructura química, hacen que los líquidos iónicos sean unos candidatos idóneos para ser utilizados en la extracción de hidrocarburos aromáticos de su mezcla con alifáticos. En la actualidad, el proceso UOP Sulfolano es el más extendido para la extracción líquido-líquido de hidrocarburos aromáticos de las gasolinas de reformado y pirólisis. Sin embargo, este proceso presenta como principales desventajas un alto consumo energético y la necesidad de recuperar el sulfolano disuelto en la corriente de refinado. La sustitución del sulfolano como disolvente extractivo por los líquidos iónicos podría superar estos inconvenientes al operar estos últimos a temperaturas más bajas, al facilitarse también la recuperación de los hidrocarburos aromáticos y la regeneración del líquido iónico y al evitarse la pérdida del disolvente extractivo en la corriente de refinado por ser los líquidos iónicos insolubles en los hidrocarburos. "Objetivos" El principal objetivo de esta tesis doctoral es la caracterización y el estudio de los líquidos iónicos como disolventes alternativos en el proceso de separación de los hidrocarburos aromáticos de su mezcla con alifáticos mediante el proceso de extracción líquido-líquido. Se persigue conseguir un disolvente con unas propiedades tanto físicas como extractivas superiores a las que presenta el sulfolano..

Determinación de la eficiencia de tres especies macrófitas para el tratamiento de aguas residuales domésticas

En la presente investigación, se da a conocer a los humedales artificiales de flujo subsuperficial como una alternativa para el tratamiento de las aguas residuales domésticas. Para ello, se determinó las eficiencias de tres especies macrofitas: Typha domingensis (totora), Phragmites australis (carricillo) y Schoenoplectus americanus (junco) sembrados en tres sistemas de humedales artificiales de flujo subsuperficial para el tratamiento de las aguas residuales; las muestras de agua residual se obtuvieron de la Planta de Tratamiento de Aguas Residuales Domésticas Maria Reiche del distrito de Miraflores y fueron tomadas a la salida de la unidad de Pre - Tratamiento. Se instaló un reservorio para el almacenamiento y distribución del agua residual hacia los sistemas de humedales. La especie Typha domingensis (totora) fue sembrada en el primer sistema (H1); la especie Phragmites australis (carricillo), en el segundo sistema (H2); y la especie Schoenoplectus americanus (junco), en el tercer sistema (H3). El tiempo de retención en cada sistema fue de 48 horas. Se determinó la calidad del agua residual antes del ingreso a los humedales y a la salida en cada sistema. La eficiencia de remoción de la Demanda Bioquímica Oxígeno (DBO) fue de 86.7 %, 83.4 % y 87 % para Typha domingensis (totora), Phragmites australis (carricillo) y Schoenoplectus americanus (junco) respectivamente; para la DQO se obtuvo, 70.37%, 72.85 % y 70.12 % en cada uno; para el caso de los Fosfatos, 43.89 %, 35.91 % y 47.96 %; para los Aceites y grasas, 97.10 %, 95.91 % y 96.90 %. Otros parámetros analizados (parámetros básicos, Amonio, SST,) mostraron valores aceptables a la salida de los sistemas

Thermal stability of choline chloride deep eutectic solvents by TGA/FTIR-ATR analysis

Deep eutectic solvents (DESs) based on the cation choline have been proposed to date for a variety of applications due to their remarkable physicochemical properties. The thermal stability is one of the first properties of DESs that needs to be known since it limits the maximum operating temperature for which these solvents are useful in many applications. In this work, the thermal stability of eight different choline chloride-based DESs formed using levulinic acid, malonic acid, glycerol, ethylene glycol, phenylacetic acid, phenylpropionic acid, urea, and glucose as hydrogen bond donors (HBDs) has been studied using isothermal and dynamic thermogravimetric analysis/Fourier transform infrared-attenuated total reflectance spectroscopy (TGA/FTIR-ATR) techniques. Isothermal and dynamic FTIR-ATR were carried out to confirm the formation and to show the structural changes with temperature of the DESs, respectively. The onset decomposition temperatures of the DESs were obtained from dynamic TGA. However, the maximum operating temperatures determined by isothermal TGA in long-term scenarios have demonstrated to be significantly lower than the onset decomposition temperatures for every DES studied. The thermal stability and the boiling point of HBDs have a crucial impact on the maximum operating temperature of DESs.publishe

Imidazolium and pyridinium-based ionic liquids for the cyclohexane/cyclohexene separation by liquid-liquid extraction

The separation of olefins/paraffins is a challenge for the petrochemical industry due to the close boiling points of these hydrocarbons. In this work we have studied the feasibility of different imidazolium and pyridinium-based ionic liquids (ILs) as alternative solvents in the cyclohexane/cyclohexene separation. Five ILs have been studied, namely 1-butyl-4-methylpyridinium tricyanomethanide ([4bmpy][TCM]), bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate ([emim]2[Co(SCN)4]), bis(1-butyl-3-methylimidazolium) tetrathiocyanatocobaltate ([bmim]2[Co(SCN)4]), 1-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4empy][Tf2N]), and 1-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4bmpy][Tf2N]). Experimental liquid-liquid equilibrium (LLE) data were obtained for the equimolar ternary mixtures {cyclohexane (1) + cyclohexene (2) + IL (3)} at T = (298.2, 313.2 and 328.2) K and atmospheric pressure in order to study the effect of the temperature on the extractive properties. Afterwards, LLE data for every ternary system was determined at the best temperature and for the whole cyclohexane/cyclohexene composition range. These ILs have shown promising results in terms of distribution ratio and selectivity, showing the [4bmpy][TCM] IL the best extractive properties at 298.2 K and atmospheric pressure. The Non-Random Two Liquids (NRTL) model was used to successfully correlate the experimental LLE data.publishe

Novel process to reduce benzene, thiophene, and pyrrole in gasoline based on [4bmpy][TCM] Ionic Liquid

This document is the accepted version of a published work that appeared in final form in Energy Fuels copyright © American Chemical Society after peer review and technical editing bu the publisher. to access final edited work see Novel Process to Reduce Benzene, Thiophene, and Pyrrole in Gasoline Based on [4bmpy][TCM] Ionic Liquid Marcos Larriba, Noemí Delgado-Mellado, Pablo Navarro, Roberto Alcover, Cristian Moya, José Palomar, Julián García, and Francisco Rodríguez Energy & Fuels 2018 32 (4), 5650-5658 DOI: 10.1021/acs.energyfuels.8b00529Regulations on benzene-, nitro-, and sulfur-containing aromatic hydrocarbon content in commercial gasolines are becoming more restrictive due to environmental and health issues. The benzene content in reformulated commercial gasoline is currently around 1%. The reduction of benzene levels to comply with future regulations will imply significant changes in refinery configurations. This paper reports a novel extraction process to simultaneously separate benzene, thiophene, and pyrrole from a gasoline using the 1-butyl-4-metylpyridinium tricyanomethanide ([4bmpy][TCM]) ionic liquid (IL). A distillation sequence is also proposed for the isolation of the three aromatic hydrocarbons. The conceptual design of the whole process has been based on experimental data from the liquid-liquid extraction and vapor-liquid separation of benzene, thiophene, and pyrrole from isooctane using the IL [4bmpy][TCM]. A COSMO-based/Aspen Plus methodology has been used to simulate the conceptual design. The a priori COSMO-based/Aspen Plus approach was validated by comparison with the experimental liquid-liquid extraction results and conventional simulations based on experimental distribution ratios and K values. Benzene, thiophene, and pyrrole contents in the gasoline would be reduced from 5.0% to 0.1% using the proposed process with a solvent-to-feed mass ratio of 5.0, and also three streams with high content in each aromatic would be obtained. Increasing the solvent-to-feed mass ratio above 5.0, benzene content in the treated gasoline could be reduced up to 200 ppm.The authors are grateful to Ministerio de Economía y Competitividad (MINECO) of Spain and Comunidad Autónoma de Madrid for financial support of Projects CTQ2014–53655-R and S2013/MAE-2800, respectively. N.D.M. thanks MINECO for her FPI grant (Reference BES–2015–072855) and M.L. also thanks MINECO for his Juan de la Cierva-Formación Contract (Reference FJCI-2015-25343). P.N. thanks Fundação para a Ciência e a Tecnologia for awarding him a postdoctoral grant (Reference SFRH/BPD/117084/2016

Relationship between variables mediating teacher performance and educational outcomes: An approach to school leadership

Este artículo estudia la relación entre variables mediadoras del desempeño docente y resultados educativos de escuelas primarias según referentes estandarizados de calidad en Chile. La muestra está constituida por 213 docentes de 50 centros escolares de la región de La Araucanía. Para la medición de las variables mediadoras: condiciones de trabajo, motivación del profesorado y habilidades para la enseñanza, se utilizó un cuestionario tipo escala likert. El estudio demuestra que existe relación entre variables mediadoras y resultados educativos. Esta relación es más significativa en la variable habilidades para la enseñanza, lo que implica el desafío de asumir un liderazgo pedagógico.This paper raises the relation between the mediating variables of teacher performance and the educational results of primary schools concerning the standardized references of quality in Chile. The sample of this study consisted of 213 teachers who belonged to 50 schools from Araucanía Region. To measure mediating variables: working conditions, teacher motivation and teaching skills, two Likert Scale Questionnaires were used. This study demonstrates a relation between the mediating variables and the educational results. This relationship is stronger regarding teaching skills variable, which implies the challenge of assuming a pedagogical leadershi

COSMO-based/Aspen Plus process simulation of the aromatic extraction from pyrolysis gasoline using the {[4empy][NTf2] + [emim][DCA]} ionic liquid mixture

The ionic liquids (ILs) have been widely studied as potential replacements of conventional solvents in the extraction of aromatic hydrocarbons from alkanes. However, most of the literature is focused in obtaining liquid-liquid equilibria experimental data without studying the complete extraction and IL regeneration process. In this paper, a computer-aided methodology combining COSMO-based molecular simulations and Aspen Plus process simulations has been used to study the extraction process of aromatic hydrocarbons from pyrolysis gasoline employing a binary mixture of 1-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4empy][NTf2]) and the 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) ILs as solvent. An extensive comparison (more than 600 points) between experimental data and the predictions obtained by the COSMO-based thermodynamic model of liquid–liquid and vapor–liquid equilibria and ILs physical properties was made for validation purposes. Process simulations were performed in three system configurations: with one, two, or three flash distillations in the IL recovery section. The potential advantage of using binary IL-IL mixture as extracting solvent was studied in the whole range of composition. The configuration with three flash distillations and the binary IL-IL mixture with a 75% of [4empy][NTf2] were selected as the optimal conditions to increase aromatic recovery and purity, improving the separation performance respect to the neat ILsThe authors are grateful to Ministerio de Economía y Competitividad (MINECO) of Spain for financial support of Projects CTQ2014-52288-R and CTQ2014–53655-R and to Comunidad Autónoma de Madrid for the Project S2013/MAE-2800. Noemí Delgado-Mellado also thanks MINECO for awarding them an FPI grant (Reference BES–2015–072855) and Marcos Larriba also thanks MINECO for awarding him a Juan de la Cierva-Formación Contract (Reference FJCI-2015-25343). Pablo Navarro thanks Fundação para a Ciência e a Tecnologia for awarding him a postdoctoral grant (Reference SFRH/BPD/117084/2016)

Exploring the accessibility of deformed digital heritage models

The concept of accessibility has been examined by the scientific community in various fields such as education, health care, social inclusion, disabilities, transport, and tourism. Regarding heritage, the European Commission’s efforts toward accessible cultural heritage are highlighted, along with the use of digitisation and modelling technologies for complex heritage shapes. Thus, this chapter explores relevant scientific research into the accessibility of digital heritage models that represent the assets’ real condition, that is, as-is or as-built models produced using advanced digitisation and modelling technologies. The study emphasises the importance of both physical and semantic aspects of heritage conservation and the need for public awareness and cooperation toward the aimed accessibility. The methodology addresses the search for publications in Scopus and Web of Science and their filtering based on inclusion and exclusion criteria to ensure documents related to the accessibility of deformed digital heritage models are considered. The research concludes that creating accessible deformed digital heritage models is crucial for inclusion and participation from the public and stakeholders, and while some studies achieve accurate as-built geometries and accessibility, there is room for improvement

Squamous cell carcinoma related with dental implants. A clinical cases report

One third of all cases of head and neck carcinoma (CA) concern the oral mucosa. The use of dental implants (DI) for dental rehabilitation is widely extended. However, a few studies have reported some cases with neoplasic alterations, among the tissue surrounding implants. Our aim was to analyze possible alterations at the bone-implant interface in patients with oral squamous cell carcinoma (SCC), providing new evidence that could relate or discard a possible link between these factors. We used, for the first time, different techniques, including electron microscopy and histology, to analyze the implant ´s surface and the surrounding tissue from four clinical cases with neoplasic alterations surrounding DI. Histologically, ample inflammatory tissue was found in direct contact with the implant surface. Surface analysis of this tissue, revealed titanium percentages. According to our study, no oncological relation with deterioration of the implant surface was found, although DI were constantly related with peri-implantitis, a chronic trauma of the oral mucosa that could involve a neoplastic factor